A disposable diaper generally has a one-piece, vertically long absorbent member disposed on an area from the rear portion, through the crotch portion, to the front portion. Elastic members are usually arranged on the leg portions to give an improved fit to wearer's legs for leakage protection.
In conventional disposable diapers, the leg portions contract with contraction of the elastic members whereas the absorbent member is not so contractible in its longitudinal direction because of its stiffness. As a result, the absorbent member sometimes becomes baggy (swelling outward) by the excess length while worn, which can cause inconveniences such as liquid's staying in the crotch portion, overhydration, and leakage. Because so-called fitted type (tape type) disposable diapers, in particular, are generally folded widthwise and compression packaged in a bag as folded for distribution and sale, the absorbent member gets oddly creased and more liable to bagging out when the diaper is worn.
JP-A-11-216161 proposes a disposable diaper in which an absorbent core is divided along imaginary lines extending in the diaper length direction and also along imaginary lines perpendicular to those imaginary lines. The absorbent core has a particle layer made mainly of a superabsorbent polymer and a fiber layer underlying the particle layer. If absorption by the particle layer results in gel blocking, further transfer of liquid to the fiber layer would be hindered. The division of the absorbent core aims to make the fiber layer capable of direct absorption from the side faces and to increase the total absorption area of the core. To achieve the aims, the gaps between divided sections of the core should be retained during use of the diaper. Therefore, the proposed disposable diaper is incapable of preventing bagging of the absorbent member and the resultant inconveniences while worn.